function validateNumber(event) {
    var key = window.event ? event.keyCode : event.which;

    if (event.keyCode == 8 || event.keyCode == 44
     || event.keyCode == 37 || event.keyCode == 39) {
        return true;
    }
    else if ( key < 48 || key > 57 ) {
        return false;
    }
    else return true;
};